It is quite apparent, from a study of the situation and the interests involved, that changes might be demanded in the bridges which would give some added advantage to river navigation, but yet would place so great a burden upon the interests concerned in crossing the river that the result would be a net loss to the general public. The following are the two extreme positions somewhere between which all concerned would agree that a balance of interests most beneficial to the general public must be determined:
Wharf at Cologne, showing heights of boats
From the viewpoint of traffic across the river the best arrangement would be level bridges at the grade of the connecting streets, regardless of river traffic. The more bridges are raised above that standard, apart from any question of first cost, the greater will be the interference with travel across the river, up to the point of prohibitive grades on the bridges and their approaches. Before this point is reached drawbridges must be considered which, while often required and adopted, are objectionable to the interests using the bridges and those passing under or through the bridges.
From the viewpoint of the river interests the most complete improvement would be to do away with the bridges entirely, thus giving absolute freedom of navigation. This is out of the question. The next best thing from that point of view would be to change the bridges to one span each across the river from bank to bank with height enough for passage beneath of the highest floating structures at all stages of the river. This would be impracticable without remodeling the city along both sides of the river for long distances from the banks at an expense so great as to be almost beyond computation. Anything less than this will impose, at least in theory, some hindrance upon river navigation, and this hindrance will be greater in amount as the head room is decreased and as piers are introduced into the river.
The aim in arriving at a solution of the bridge problem must be to adjust these conflicting interests impartially; and the factors to be considered in arriving at such an adjustment are these: First, the amount and importance of the traffic likely to be affected in each case. Second, the extent to which any given solution would benefit or injure the bridge traffic and the river traffic, respectively.
1. Amount and Importance of Traffic Affected.—(a) Bridge Traffic.—There are in question six highway bridges and two railroad bridges.
| UNDER BRIDGES | OVER BRIDGES | |||
|---|---|---|---|---|
| TONNAGE IN MILLIONS | ||||
| ██ | 2,344,398 | SIXTH ST. | 13,240,010 | ████████ |
| ██ | 2,796,122 | NINTH ST. | 14,732,130 | █████████ |
| █ | 2,228,270 | FT. WAYNE. | 53,127,210 | ████████████████████████████████████ |
| ▊ | 1,045,570 | THIRTIETH ST. | 398,430 | ▎ |
| ▋ | 865,024 | JUNCTION RR. | 24,335,982 | ████████████████▌ |
| ▐ | 714,856 | FORTY-THIRD ST. | 311,090 | ▎ |
| PASSENGERS IN MILLIONS | ||||
| ▕ | 25,680 | SIXTH ST. | 27,098,291 | ████████████████████████████████████ |
| ▕ | 30,567 | NINTH ST. | 24,325,900 | ████████████████████████████████▌ |
| ▕ | 24,408 | FT. WAYNE. | 4,877,495 | ██████▌ |
| ▕ | 11,455 | THIRTIETH ST. | 715,985 | █ |
| ▕ | 9,475 | JUNCTION RR. | 217,254 | ▎ |
| ▕ | 7,831 | FORTY-THIRD ST. | 816,333 | █ |
| UNDER BRIDGES | OVER BRIDGES | |||
| Diagram No. 1, showing comparative importance of traffic over and under Allegheny river bridges | ||||
108,000,000 TONS
OVER BRIDGES
1,500,000
TONS
UNDER
BRIDGES